How dim is the screen? Make sure the brightness is turned up. Make sure the connector are properly connected. You could try a soft reset. Does the LCD display an image when it goes to the home screen, or do you have to be in light or turn the iPad a certain way to see what's on the display, if that's the case the black light fuse may need to be replaced.
Did you use gloves during the repair because the oil on your fingers on those gold connections can cause you some problems. Clean all the connector or gold parts with some alcohol, and put bad together. Also the iPhone 5 speakers are a little tricky you have to make sure that metal connected correctly so the metal points on your cable are touching the correct location of your speaker
First is your data backed up to the cloud? You can check and see what's on your iCloud by going to iCloud.com this is step1. Any time your doing a repair it could cause damage to the phone that's why you should back the phone up via the cloud. If your phone gets damaged then put in your Apple ID in the new phone and everything that is backed up to the cloud will be in your new phone
Could be a memory problem, delete some old pictures and video and make sure you have at least 1.0 GB left that should keep everything running smooth. Then got reset on the phone hold down the home button and push and hold power button hold both buttons until the apple icon comes on and see what happens. Make sure the phone software is up to date as well!!
Take a suction cup and stick that on the screen and then pull up on the section cup this will put some pressure on that screew, keep pressure by pulling up on the screen and the screw should turn out, pretty common problem
That's a strange problem did you try to lock the screen? While on the home screen Swipe up from the bottom from the screen which will display some options, the lock icon is at the top of this option box and has a lock with a circle around it. See if that helps!
I had a very similar situation with a iPhone 6, no Touch ID after doing a screen replacement. Checked everything and nothing was damaged, tried a another screen had the same results. The next time the customer did a IOS update it started working?!!